The present invention relates to a track and hold circuit, and a related receiving device with the track and hold circuit employed therein, and more particularly to an arrangement for improving problems of kick-back noise and signal distortion in a track and hold circuit, and a related receiving device.
In a wireless receiving system, a track and hold circuit is utilized to track a down converted intermediate frequency signal and maintain the value of the track signal for a predetermined time interval. Then, an analog-to-digital converter (ADC) converts the track signal into a corresponding digital signal. The corresponding digital signal is provided to determine if the voltage level of blocker signal received by the wireless receiving system is within a predetermined range. If the digital signal indicates that the voltage level of the received blocker exceeds the predetermined voltage range, an adjusting mechanism is employed to adjust the gain of a front-end stage and/or a back-end stage of the wireless receiving system in order to receive the RF signal precisely. However, since the track and hold operation of the track and hold circuit is accomplished by controlling a plurality of switches in the track and hold circuit, the charge injection generated by the plurality of switches may result in a kick-back noise to the front-end stage and the back-end stage of the wireless receiving system when the track and hold circuit tracks and holds the down converted intermediate frequency signal, consequently affecting the signal-to-noise ratio and distortion ratio of a base-band signal generated by the back-end stage. In addition, the charge injection generated by the plurality of switches may introduce some distortion upon the track signal and the corresponding digital signal, which in turn affects the receiving capability of the wireless receiving system. Therefore, providing a clean and low distortion track and hold circuit in the wireless receiving system is desirable.